Note: Descriptions are shown in the official language in which they were submitted.
ELECTROMAGNETIC HA~ER ACTUATOR FOR IMPACT PRINTER
FIEL;.J OF INVENTION
The present invention lelates to impact printers o~~ the
type including a plurality of hammers which are actuated
selectively in order to perform printing operations on a print
medi~, for example a sheet of paper. A printer of this type
ïO :includes an actuator for eae~ hammer and the present inventior
is particularly related to electromagnetic print hammer
actuators.
BACKGROt.~D OF THE INVENTION
In one known type of printer, adapted to print on a prin-
rnedium as it passes over a platen using a plurality of printelements operated selectivel~ by hammers, the print elements
are mounted on flexible fin~ers forming part of a metal band
which is in the form of a continuous loop, one print element
being mounted on each flexible finger. The print elements
extend in a straight line along the band parallel to the
~ongitudinal center line of the band. A bank of hammers
extends along the platen an~l is spaced from the platen so as to
clefir~e a print region between the hammer bank and the platen.
l'he print medium, such as a continuous web of paper, extends
t:hrough the print region over the platen so that the ha~mer
bank extends across the width of the print medium. The metal
hand on which ~he print elenents are mounted also extends
through the print region al~ng the platen and across the width
of the print medium and is located between the hammer bank and
the print medium. An ink ribbon also is located in the print
region between the metal ban~ ~nd the print medium.
CT9-83-007 ~
rhe metal band is driven continuously past the ~laten and
the hammer bank and across the print medium by a suitable drive
system. Operation of any or,e of the hammers of the bank causes
that hammer to move towards the metal band and to strike one of
S the print elements so as to move that print element on its
flexible finger towards the ink ribbon and the print rnedium.
The print element abuts against the lnk ribbon, moves the ink
ribbon into contact with the print medium and presses the ink
ribbon and the print medium against the platen causing the
printing of a mark on the print medium in the shape of th~e
print element.
According to one particular printer of the above kind and
illustrated by way of example in United States Patent No.
4,428,284, each of the print elements is shaped like a dot and
~15 operation of each hammer causes the printing of a dot on the
print medium. As the metal band moves continuously across the
print medium, operation of selected hammers will result in the
printing of a row of dots ir, positions on the print medium
corresponding to the positions of the hammers which are
operated. ~ach hammer is formed with a head having a width in
the direction of movement of the band which is greater than the
width of a single print element. It is therefore possible for
each hammer to print a dot in any position on the print medium
which is covered by the hamm~r by varying the timing of the
operation of the hammer relative to the movement of the band.
As a result, the dots in the row printed can occupy many
selected positions on the prLnt medium. There is only a small
gap between each pair of ad~acent hammer heads and the hammers
can therefore print dots at all required positions along the
row being printed.
After one row of dots has been printed the print medium
can be moved through a small increment transversely to the
length of the platen and the operation can~be repeated
r,esulting in the printing o~ a second row of dots spaced from
3~ the first row of dots. By xepeating these operations rows of
dots can be printed as required.
c~rg-83-007X -2-
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A character can be printed on the medium by printing dots
in selected positions in a matrix, for example a ma~rix cf five
colunms and seven rows. By printing dots in se]ected positions
in rows as described above and selectively moving the print
medium, characters can be printed in s~lected positions on the
mediumO
In the printer described above the hammers are mounted
together to form a hammer bank which extends along the platen.
Each hammer is formed with a head and is associated with a
respective actuator which has a finite width. It is desirable
for the heads of adjacent hammers to be spaced apar~ by only a
small distance so as to be able to print dots substantially at
all positions along a row on the print medium. With such an
arrangement each hammer head will cover a plurality of
positions in which dots are .equired to be printed and
therefore each hammer will have to be operated a plurality of
times in printing a row of clots. In order to reduce the n~mber
of times that each hammer will have to be operated in printing
a row of dots, the width of each hammer must be reduced. This
requires that the width of each hammer and actuator assembly
must be reduced.
.
; Various types of printer hammer actuator are known. One
particular type with which the present invention is concerned
is described by way of example in Canadian Patent No.
; ~ 1,135,317. The printer hammer actuator described is an
electromagnetic actuator whi h includes a stator in two halves,
each provided with a coil, and a moving armature member which
is located between the two stator halves. The armature member
is formed from a non-magnetizable material, for e~ample a
synthetic plastic material, and is flat with a rectangular
cross section. The armature member is provided with a
plurality of a~-mature elements of magnetizable material. ~he
armature elements are spaced apart along th-e length of the
armature member. The armature member is provided with
longitudinally extending ribs to add to its strength and to
guide it during operation. A hammer head is formed at one end
of the armature member.
CT9~83-007~ -3-
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T~.e stator of the actua~or is formed in two halves with
pole pieces extending towards each other in pairs a~ld spaced
apart so as to form a set of gaps in which the armature member
is located. When the armature member is in the rest position
each of the armature elements in the armature member is
slightly spaced from a respective o`ne of the pairs of pole
pieces of the stator. When the coils of the stator are
energized, a flux is generated which flows between the pairs of
pole pieces and through the armature elements. As a result
each armature element is attLacted to the adjacent pair of pole
pieces and a longitudinal force is exerted on the armature
member. The armature member is retained in lts rest position
by a spring. The longitudin~-ll force causes the armature member
to move against the action of this spring and allows the head
on the armature to perform a printing operation.
. . ~ ~
Canadian Patent No. 1,185,317 also describes assembling a
plurality of actuators of this kind side by side to form a
hammer banX. The armature elcments on the armature members of
adjacent actuators are located at opposite ends of the armature
members. As a result the stator coils of adjacent actuators
are also located at opposite ends of the actuators. With this
arrangement the stator coils are interleaved and thereby~reduce
tne overall length of the hammer bank.
United States Patent No. 4,371,857 describes a similar
type of hammer actuator in which the armature member is
circular in cross section and the stator is formed in two
halves. In one arrangement the stator is illustrated as having
a coil' on only one half.
IBM Technical Disclosure Bulletin Volume 25, No. llB,
April i983 at page 6184 also describes a similar type of
actuator in whi~h the stator is formed in two halves with a
coil on only one half.
IBM Technical Disclosure Bulletin Volume 25, No. llB,
April 1983 at pages 6284, 6285 describes a bank of print hammer
actuators of the above type in which the actuators are arranged
CT9-83-007X ~4~
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side by side. The armature elements and stator coils of
adjacent actuators are located at opposite ends of the armatu:_
members so that the stator coils are interleaved and thexeby
reduce the overall length of the hammer bank.
United Sta~es Patents Nos. 4,351,235 and 4,082,035
describe printers which are formed with banks of hammer
actuators. Each hammer actuator includes an armature member o~
magnetizable material which cooperates with a stator provided
with a coil. Each armature member is formed with a hammer head
at one end and all the hammer heads of the actuators in ~he
ban~ extend along a line. The actuators are located on both
sides of this line with adjacent actuators on opposite sides.
~'ith this arrangement the stator coils are interleaved and
thereby reduce the overall length of the hammer bank.
The object of the preseat invention is to provide an
improved assembly of electrornagnetic printer hammer actuators.
S~M~I~RY OE THE INVENTION
. _ _
The present invention relates to an assembly of
electromagnetic actuators for the hammers of an impact printer
arranged side by side and extending along a line. Each
actuator comprises a first stator part formed with at least one
pole piece, a second stator l~art formed with at least one pole
piece and positioned re~ative to the first stator part so that
the pole pieces are spaced a~:~art so as to form a gap
therebetween, and a single coil associated with one of the
stator parts. Each actuator also includes an armature member
formed with a body of non-magnetizable material, at least one
armature element of magnetizable material and a hammer head.
The armature member is supported between the stator parts so
that the armat~re element is located adjacent to the gap
between the pole pieces. Energization of t-he coil causes the
generation of a flux which passes across the gap and through
the armature element tendiny to move the armature element into
the gap and to cause the hammer head to move into a print
position.
C'I'9-83-007X
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According to the invention the components of adjacent
actuators are complementary in shape so that projecting
components of each actuator engage in recessed components of
the adjacent actuators whereby the overall length of the
assembly along the line is less than the sum of the overall
widths of the individual actuators.
According to one embodiment of the invention, in each
actuator the coil is associated with the first stator part, and
the second stator part includes a component having a wid~h less
than the width of the coil. In adjacent actuators the coil is
located at the top of one actuator and at the bottom of the
other actuator so that the coil of each actuator engages in the
component of the adjacent actuator having a width less than the
- width of the coil.
,
1~ According to ano~her embodiment of the invention the body
of each armature member includes a relatively wide portion in
which is located the armature element and a relatively narrow
portion. In adjacent actuators the relatively wide portion of
the armature member is located near one end of the body in one
,~ actuator and near the opposite end of the body in the other
actuator so that the relatively wide portion of the armature
member of each actuator engages in the relatively narrow
portion of the armature member of the adjacent actuator.
BRIEF DESCRIPTION OF THE DRAWINGS
~hese and other objects, features and advantages of the
invention will be more fully understood by those working in the
art by reading and understancling the following description of a
preferred embodiment of the invention, wherein reference is
made to the accompanying dra~ings of which:
Fig. 1 is a diagrammatic side view of~a hammer actuator
including a stator and an armature member,
Fig. 2 is a plan view oE the armature member used in the
actuator illustrated in Fig. 1,
CT~-83-007 X -6-
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Fig. 3 is a plan view cl~ the lower part of the stator used
in the actuator illustrated in Fig. l,
Fig. 4 is a view from underneath of the upper part of the
stator used in the actuator illustrated in Fig. 1,
Fig. 5 ,s a perspective view of one part of the stator
used in an actuator which is a practical embodiment of the
actuator illustrated in Figs. 1, 2, 3 and 4,
Fig. 6 is a perspective view of an armature member Ased
with the stator part illustrated in Fig. 5,
Fig. 7 is a perspective view, partly cut away, of the
other part of a stator used with the stator part illustrated in
Fig. 5,
, . .. .
Fig. 8 is a perspective view of a stator coil used with
the stator part illustrated in Fig. 5,
lj Fig. 9 is a perspective view of an actuator assembled frorr
the components illustrated irl Figs. 5, 6, 7 and 8,
Fig. 10 is an end view of a plurality of actuators as
illustrated in Fig. 9 assembled to form a bank of ham~ers
embodying the invention,
Fig. 11 is a perspective view of the bank of hammers
illustrated in Fig. lO,
Fig. 12 is a perspective view of a pair of armature
members used in another practical embodiment of the actuator
illus'rated in Figs. l, 2, 3 and 4,
~v
Fig. 13 is a perspective view from underneath of the pair
of armature members illustrated in Fig. 12,
CT9-83-007X ~7~
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Fig. 14 is a perspective view of part of a stator whic-; --
used with one of the armature members illustrated in Figs. i~
and 13,
Fig. 15 is a diagrammatic side view of the stator part
illustrated in Fig. 14,
Pig. 16 is a view from underneath of the stator part
illustrated in Fig. 14,
Fig. 17 is a perspective view of another stator part used
with the armature members iliustrated in Figs. 12 and 13,
Fig. 18 is a perspective view of a block adapted to hold a
plurality of the stator parts illustrated in Figs. 14, 15 and
16,
Fig. 19 is a perspective view of a plurality of actuators
assem~led from the components illustrated in Figs. 12, 13, 14,
15, 16, 17 and 18 to form a bank of hammers embodying the
invention,
Fig. 20 is a perspective view of another pair of armature
members used in a still further practical embodiment of the
actuator illustrated in Figs. 1, 2, 3 and 4,
Fig. 21 is a perspective view from underneath of the pair
of armature members illustrated in Fig. 20,
Fig. 22 is a perspective view of a stator part for use
with the armature members illustrated in Figs. 20 and 21,
Fig. 23 is a perspective vie~ of a plurality of actuators
assembled from~the components illustrated in Figs. 20, 21 and
22 to form a bank of hammers embodying the invention.
CT9-83-007X 8-
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DETAILED DESCRIPTION OF THE INVENTI~N
Figs. 1, 2, 3 and 4 illustrate diagrammatically an
electromagnetic printer hammer actuator with which the present
invention is concerned. The actuator comprises an upper statc,r
part 1, a lower stator part 2 and an armature member 3. The
upper stator part l is generally E-shaped and is formed wlth
three legs 4, ~ and 6 which are shaped at their ends to form
four pole pieces 7, 8, 9 and ll. Around the central leg 5 is
wound a coil 12 which is adapted to be supplied with a suitable
o voltage through a s~itch (not illustrated). The lower stator
part 2 is formed on its upper surface with four legs 13, 14, 15
and 16 also forming pole pieces. The pole .l-ces 13, 14, 15
and 16 are positioned respectively under the pole pieces 7, 8,
9 and 11 of the upper stator part 1 so as to form four pole
~5 pairs with gaps bet~een the loles of each pair. As illustrated
in Figures 3 and 4 the pole pieces 7, 8, 9 and 11 and 13, 14,
15 and 16 extend across the full width of the stator parts 1
and 2~
The armature member 3 h-:lS a rectangular cross section body
portion 17 of non-magnetizable material, for example a
synthetic plastic material, and is formed with four armature
elemerits 18, 19, 21 and 22 o~ soft iron or another magneti~able
material and having a rectan~Jular cross section. As
illustrated in Fig. 2 the arr~ature elements 18, 19, 21 and 22
extend across the armature rnember 3 but do not reach quite to
the edges of the armature mernber. The armature elements 18,
19, 2I and 22 are spaced apart by distances equal to the
d~stances apart of the pole pieces 7, 8, 9 and 11 and 18, 19,
21 and 22. Therefore, if the armature member 3 is located
; -~o between the stator parts 1 and 2, each armature element can be
located adjace~t to a respective one of the pole pairs. The
outer surfaces of the armature member 3 are-coated with a layer
23 of a low friction material, such as the
polytetrafluoroethylene material known as Teflon (Registered
Trade Mark).
c~rs-83-007 ~< -9-
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~ hammer head 24 is fo.r.ned on one end of the armat~re
member 3 and at the other end a spring 25 extends between the
armature member 3 and a fixed member 26. The head 24 is
arranged to cooperate with a print element 27, an ink ribbon
28, a print medium 29 and a pl.aten 31 in order to perform
prlnting operations on the print mèdium 29.
In order to perform printing operations using the ham~er
head 24 and the actuator described, the components are
assembled so that the armature member 3 is located between the
stator parts 1 and 2 with the armature elements 18, 19, 21 and
22 positioned just to the le~t of the respective pole pairs 7
and 13, 8 and 14, 9 and 15, 11 and 16, as viewed in
Fig. 1. With the armature member 3 in this position, the head
24 is spaced from the print element 27. If the coil 12 is
.5 energized a magnetic flux wi.Ll be produced in the assembly as
illustrated by the arrows in Fig. 1. This flux will be
concen~rated at the pole pieces 7, 8, 9 and 11 and 13, 14, 15
and 16 and, in passing between the pole pairs, it will be
deflected to pass through the armature elements 18, 19, 21 and
22. The ilux will tend to cause each armature element to move
into a position in which it .i.s directly between the pole faces
of the adjacent pair o~ poles.
As a result, a longitudi.nal i.-orce will be exerted on the
a:rmature member 3 tending to move it to the right, as viewed in
Fig. 1, against the action of the spring 25. The armature
member 3 will move to the right and the head 24 will strike the
p:rint element 27. The print element 27 will move into contact
w:ith the ink ribbon 28 and mGve the ink ribbon into contact
w:Lth the print medium 29. Ihe ink ribbon 28 and the print
medium 29 will be pressed against the platen 31 causing a
printing operation to be per~ormed in which a mark in the shape
oi. the print e~ement 27 will be printed on the print medium 29.
This printing operation is f~llly described in United States
Patent No. 4,428,284 and will not be described in greater
3j detail here since it does no-t form part of the present
invention .
CT9-83-007 X 10-
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The forces exer~ed on ti~e armature member 3 by the flux
generated by the coil 12 are partly longitudinal forces and
partly transverse forces. The longitudinal forces are used to
move the armature member 3 i.ongitudinally in order to p -form
the printing operation described above. The transverse forces
will tend to move the armature memBer into close contact with ;
the stator parts 1 and 2. This action would tend to exert
frictional forces on the armature member 3 which would
interfere with the printing operation. By coating the armature
member 3 with the layer 23 of low friction material, the~e
frictional forces are apprec-iably reduced. The layer 23 covers
all the outer surfaces of tile armature elements 18, 19, 21 and
22 and therefore there is no metal to metal contact between the
armature member 3 and the stator parts 1 and 2.
In a practical embodimenk oî an actuator as described
above the coating layer 23 ~s a thickness of 0.13 mm (0.0005
in) and the length of each o.- the legs 13, 14, 15 and 16 is 0.4
mm (0.016 in).
Figs. 5, 6, 7, 8 and 9 i.llustrate an actuator which is a
practical embodiment of the actuator illustrated in Figs. 1, ~,
3 and 4. The actuator comprlses an upper stator part 41, a
lower stator part 42, a stator coil 43 and an armature member
44. The upper stator part 41 is generally E-shaped with three
legs 45, 46 and 47 terminating in four pole pieces 48, 49, 51
and 52. The coil 43 is formed around a central hole 50 and is
shaped so as to fit round the central leg 46 of the upper
stato~ part 41. The lower s~-ator part 42 is generally ~-shaped
in cross section with a lower leg portion 53, a central portion
~4 extending at right angles to the leg portion 53 and two
^o upstanding side portions 55 and 56. The central portion 54 is
substantially planer, that i.s, having an overall thickness
narrower than ~--he thickness of coil 43, and is formed with four
upstanding legs forming pole pieces 57, 58,- 59 and 61 which
extend across the width of t:ile central portion 54 between the
side portions 55, 56. The central portion 54 and the pole
pieces 57, 58, 59 and 61 of iower stator part 42 are
constructed of a soft magnetizable material such as silicon
iron whereas the lower leg portion 53 and the side portions 55
CT9-83-307X
1~ 32~
and ~6 are constructed of a non-magnetizable materlal such as a
synthetic plastic. The pol~ pieces 57, 58, 59 and 61 are
spaced apart by the same distances as the pole pieces 48, 49,
51 and 52. The armature me~-nher 44 has a rectangular cross
section body portion 62 of a non-magnetizable material, for
example a synthetic plastic rnateriàl, and four armature
elements 63, 64, 65 and 66 oE magnetizable material within the
body portion 62. The armature elements 63, 64, 65 and 66 are
spaced apart by the same distances as the pole pieces 57, 58,
iO 59 and 6i. The body portion 62 of the arm~ture member is
coated with a layer of low friction material, for example the
polytetrafluoroethylene material known as Teflon (Registered
Trade Mark). For clarity of Fig. 6 this layer is not
illustrated. At one end of the armature member 44 is formed a
hammer head 67.
.. . .
Fig. 9 illustrates -the actuator fully assembled. The
armature member 44 is located on the central portion 54 of the
lower stator part 42. The c~istance between the inner surfaces
of the side portions 55 and 56 is slightly greater than the
width of the armature member 44. The distance between the
faces of each pole pair 48 and 57, 49 and 58, S1 and 59 and 52
and 61 is slightly greater than the thickness of the armature
member 44 in the vertical direction. As a result, the armature
member 44 is constrained to move longitudinally with the side
portions 55 and 56 and the pole faces acting as guides. The
overall width of the coil 43 is greater than the distance
between the outer surfaces of the side portions 55 and 56 so
that the coil projects beyond these side portions. The
movement of the armature member 44 is controlled as described
with reference to Figs. 1, 2, 3 and 4.
Figs. 10 and 11 illustrate how five of the actuators
illustrated in Fig. 9 can be assembled to form a hammer bank
embodying the invention. The actuators, labelled A, B, C, D
a~d E and cross hatched in different ways in order that the
3~ components of individual actuators can be more clearly
distinguished, are assembled with the stator parts 41 and the
coils 43 of adjacent actuators located on opposite sides of a
crg-83-007 X -12-
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central line X - X on which are located all the armature
members 44 and the hammer h~ads 67. Each hammer head 67 is
spaced apart from the adjacent hammer head by a small distance
so as to allow the hammer heads to move freely relative to one
S another. It will be seen that the components of adjacent
actuators are complementary ,in shape so that projecting
components of each actuator engage in recessed components of
the adjacent actuator. The projecting outer side surfaces of
each coil 43 extend towards and are spaced a small distance
from the recessed leg portiolls 53 of the adjacent actuators.
The overall length of the hainmer bank in the direction o- the
line X ~ X is therefore less than the sum of the widths of the
individual actuators. The hammer bank is therefore very
compact.
~ach coil 43 has a relatively large volume so that there '
is a minimum of heat generation in each coil and good heat
dissipation.
The configuration of each actuator allows the armature
m~ember 44 to be relatively short, thereby reducing the mass of
,o the armature member. The recluced mass increases the
acceleration for the same ap21ied foree. The printing i.mpact
is unaffeeted due to the eompensating effects of the reduction
c,f mass and the increase in velocity.
In a practical embodiment of a hammer bank as illustrated
in Figs. 10 and 11 the mass of each armature member 44 was l5C
mg and the width of each ha~-ner head was 7.62 mm (0.3 in). The
average acceleration force imparted to each armature member for
a~travel of 0.178 mm (0.007 in) was 5 Newtons. If a maximum
working gap of 0.51 mm (0.02') in) is assumed, a repetition rate
for operation of each of the actuators of 2000 cycles per
second would b~ achievable.
Figs. 12, 13, 14, 15, 16, 17 and 18 illustrate another
aetuator which is a practical embodiment of the actuator
illustrated in Figs. 1, 2, 3 and 4. Figs. 12 and 13 illustrate
two forms 71, 72 of the armature member of the actuator which
CT9-83-007 X -13-
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are adapted to be assembleci close together. ~rma-ture member 71
comprises a body 73 of a ncn-magnetizable material having a
relatively wide middle portion 74 in which are located four
armature elements 75, 76, 77 and 78 of magnetizable material, a
relatively narrow tail portion 79 formed with a hole 81 and a
relatively narrow curved neck portion 82 to the end of ~hich ~s
attached a hammer head 83. The tail portion 79 is longer than
the neck portion 82. The other armature member 72 also
comprises a body 84 of a non-magnetizable material havins a
relatively wide middle portion 85 in which are located four
armature elements 86, 87, 8;3 and 89 of magnetizable mate~ial, a
relatively narrow tail portion 91 formed with a hole 92 and a
relatively narrow curved neck portion 93 to the end of which is
attached a hammer head 94. The tail portion 91 is shorter th~n
i5 the neck portion 93. As illustrated in Fig. 13 the under
surface of each of the armature members 71, 72 is formed with a
longitudinal rib 95 and the armature elements extend through
the full thickness of each armature member. It will be seen
that the two armature members 71 and 72 are complementary in
shape so that, if the armat~1re members are placed side by side,
projecting components of each armature member engage in
recessed components of the other armature member. This is
illustrated in Figs. 12 and 13. The relatively wide middle
portion of each armature member engages in the recess formed by
t:he relatively narrow tail portion or the relatively narrow
neck portion of the other armature member so that the two
armature members can be placed very close together.
Figs. 14, 15 and 16 illustrate a stator part 101 to be
used with each of the armature members 71 and 72. Each stator
part 101 comprises a yoke 102 and a coil 103. As seen most
clearly in Figure 15, the yoke 102 is shaped so as to form four
pole pieces 104, 105, 106 and 107 which are spaced apart by the
same distances~as the armature elements 75, 76, 77 and 78 and
86, 87, 88 and 89.
Fig. 17 illustrates ano-ther stator part 108 to be used
with the armature members 71 and 72. Stator part 108 is a flat
rectangular block 109 formed on its upper surface with a
CT9-83-007 X -14-
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plurality of parallel grooves 110 and two sets of pole pieces
or parallel ridges 112 and l13 extending at right angles to th--
grooves llO. The ridges 112 are spaced apart by distances
equal to the spacing of the armature elements 75, 76, 77 and 78
of the armature member 71 and the ridges 113 are spaced apart
by a distance equal to the spacing`of the armature elements 8~,
87, 88 and 89 of the armature member 72. Guide members 114 are
located at various positions on the upper surface of the blocX
109 adjacent to the grooves 110 as indicated.
Fig. 17 illustrates one armature member 71 and one
armature member 72 in positl~n on the upper surface of the
block 109. Each armature member is located in position by its
longitudinal guide rib 95 el~gaging in one of the grooves llO
and the sides of the armature~ member engaging with the guide
members 114. If the armature member 71 is accurately
positioned so that its armature elements 75, 76, 77 and 78
coincide with the ridges 112 and the armature member 72 is
accurately positioned so that its armature elements 86, 87, 88
and 89 coincide with the riclges 113 the wide middle portion 74
of armature member 71 will engage in the recess formed by the
narrow neck portion 93 of armature member 72 and the wide
middle portion 85 of the armature member 72 will engage in the
recess formed by the narrow tail portion 79 of the armature
member 71. The width of the region on the upper surface of the
block 109 occupied by the armature members 71 and 72 will be
less than the sum of the overall widths of two armature
members.
Fig. 18 illustrates a hlock 121 adapted to hold a
plurality of stator parts of the type illustrated in Figs. 14,
15 and 16. The block 121 is formed with seven holes 122
arranged in two rows as illustrated, with three holes 122 in
the row nearer~the front of the block and four holes 122 in the
row nearer the back of the block. ~ach hol-e 122 is formed with
a ledge 123 at the front and the back. At the back of the
block are supported seven springs 124 which extend down into
the block.
CT9~83-007 X -15-
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Fig. 19 illustrates how three of the armature members 71
and four of the armature merlit)ers 72, seven of the stator parts
101, one block 109 and one block 121 can be assembled to form a
hammer bank embodying the invention. As illustrated, the three
armature members 71 with their hammer heads 83 are positioned
on the block 109 with their ribs 9S engaging in alternate
grooves 110 so that the heacls 83 project beyond the front edge `
of the block 109. In this p~sîtion the wide middle portion 74
of each armature member 71 is located over the set of ridges
112. The four armature members 72 with their hammer heads 94
are positioned on the block 109 with their ribs 95 engasing in
alternate grooves 110 so that the heads 94 project beyond the
front edge of the block 109 and are located in between the
heads 83 of the armature memDers 71. In this position the wide
middle portion 85 of each ~rr.lature member 72 is located over
the set of ridges 113. The t,lock 121 is placed over the
armature members and the hol.es 122 in the block are positioned
so that the three holes in t~le front row coincide with the wide
middle portions 74 of the three armature members 71 and the
- 20 four holes in the rear row coincide with the wide middle
portions 85 of the four armature members 72.
A stator part 101 is located in each of the holes 122 and
the pole pieces 104, 105, 106 and 107 of tHese stator parts.
coincide with the ridges of ~he sets of ridges 112 and 113 so
as to form pole pairs of the type described above with .
reference to Figs. 1, 2, 3 and 4. The lower ends of the
springs 124 engage in the ho~.es 81 and 92 in the narrow
portions of the armature mer.i.Jers 71, 72 remote from their
hammer heads 83, 94. All the hammer heads 83 and 94 extend
aIong a line X - X.
When the armature members 71, 72 are in the rest position,
each of the ar~ature elements 75, 76, 77 and 78 and 86, 87, 88
and 89 is spaced from a respe~ctive one of the pole pairs formed
by the sets of ridges 112 and 113 and the pole pieces 104, 105,
106 and 107. If the coil 103 of any one of the stator ~rts
102 is energized, the armature elements of the associated
armature member will be attracted into the gaps between the
CT9-83-007~ -16-
adjacent pole pairs and the armature member will mvve against
the action of the associatecl spring 124. As a result, the
associated hammer head will move into a print position.
It will be appreciated that, since the wide middle portion
of each of the armature members 71, 72 engages in the narrow
portions of the adjacent armature members, the length of the
assembly of actuators along the line X - X is less than the sum
of the overall widths of al; the individual actuators. .~s a
result the assembly forming the hammer ban~ is compact.
Figs. 20, 21 and 22 il;ustrate another actuator which is a
practical embodiment of the actuator illustrated in Figs. 1, 2,
3 and 4. Figs. 20 and 21 illustrate two forms 131 and 132 of
the armature member of the actuator which are adapted to be
assembled close together. Armature member 131 comprises a body
133 of a non-magnetizable material having a relatively wide
middle portion 134 in which are located four armature elements
135, 136, 137 and 138 of maglletizable material, a relatively
narrow tail portion 139 formed with a hole 141 and a relatively
narrow curved neck portion 1~l2 to the end of which is attached
2~ a hammer head 143. The tail portion 139 is longer than the
neck portion 142. The other armature member 132 also comprises
a body 144 of a non-magnetizable material having a relatively
wide middle portion 145 in which are located four armature
elements 146, 147, 148 and 1~9 of magnetizable material, a
relatively narrow tail portion 151 formed with a hole 152 and a
r~lativel~ narrow curved nec~ portion 153 to the end of which
is attached a hammer head 15l~. The tail portion 151 is shorter
than the neck portion 153. ~s illustrated in Fig. 21 the under
surface of each of the armat~lre members 131, 132 is formed with
a longitudinal rib 155 and trle armature elements extend through
the full thickness of each armature member. It will be seen
that the two armature members 131 and 132 are complementary in
shape so that, if the armature members are placed side by side,
projecting components of each armature member engage in
recessed components of the other armature member. This is
i:Llustrated in Figs. 20 and 21. The relatively wide middle
portion of each armature member engages in the recess formed by
c'rg-83-007X -17-
~ 1~S8~
the relatively narrow tail p~rtion or the relatlveiy na row
neck portion of the other arlnature member so that the two
armature members can be placed very close together.
Fig. 22 illustrates a statox part 1~0 to be used with the
armature members 131 and 132. Stator part 160 is similar to
the stator part 108 illustrated in Fig. 17 and is a flat
rectangular block 161 forme~ on its upper and lower surfaces
with a plurality of parallei grooves llO and two sets of
parallel ridges 112 and 113 extendinq at right angles to the
grooves 110. The ridges 112 are spaced apart by distances
equal to the spacing of the armature elements 135, 136, i37 and
138 of the armature member 131 and the ridges 113 are spaced
apart by distances equal to the spacing of the armature
elements 146, 147, 148 and 149 of the armature member 132.
Guide members 114 are locatel at various positions on the upper
and lower surfaces of the block 109 adjacent to the grooves 110
as indicated.
Fig. 22 illustrates one armature member 131 and one
armature member 132 in positlon on the upper surface of the
~o block 161 and one armature member 131 and one armature member
132 in position on the lower surface of the block 161. Each
armature member is located in position by its longitudinal
guide rib 155 engaging in one of the grooves 110 and the sides
of the armature member engag:ing with the guide members 114. If
each armature member 131 is accurately positioned so that its
armature elements 135, 136, 137 and 138 coincide with the
ridges 112 and each armature member 132 is accura-tely
positSoned so that its armature elements 146, 147, 148 and 149
coincide with the ridges 113, the wide middle portion 134 of
each armature member 131 wilL engage in the recess formed by
the narrow neck portion 153 ~f the adjacent armature member
132. The widths of the reqlcns on the upper and lower surfaces
of the block 161 occupied b~ the armature ~embers 131 and 132
will be less in each case than the sum of the overall widths of
the armature members on the surfaces.
CT9-83-007~ ~18-
, ~582~
Fig. 23 illustrates ho si~ of the ar~ature members 131
and eight of the armature m~i~bers 132, fourteen of the stator
parts 101, one block 161 and two blocks 121 can be assembled to
form a hammer bank embodying the invention. As illustrated,
three armature members 131 wlth their hammer heads 1~3 are
positioned on the upper surface of block 161 with their ribs
155 engaging in alternate grooves 110 (Fig. 22) so that the
heads 143 project beyond the front edge of the block 161 and
three armature members 131 with their hammer heads 143 are
positioned on the lower surl-ace of block 161 with their ribs
155 engaging in alternate grooves 110 (Fig. 22) so that ~he
heads 143 project be~ond the front edge of the block 161. In
this position the wide middle portion 134 of each armature
member 131 is located over the set of ridges 112 (Fig. 22).
i5 Four armature members 132 with their hammer heads 154 are
positioned on the upper surt-ice of block 161 with their ribs
155 engaging in alternate grooves 110 (Fig. 22) so that the
heads 154 project beyond the front edge of the block 161 and
are located in between the heads 143 of the armature members
131 and four armature members 132 with their hammer heads 154
are positioned on the lower surface of block 161 with their
ribs 155 engaging in alternate grooves 110 (Fig. 22) so that
the heads 154 project beyond the front edge of the block-161
and are located in between the heads 143 of the armature
members 131. In this position the wide middle portions 145 of
each armature member 132 is located over the set of ridges 113
(Fig. 22). One block 121 is placed over the armature members
on the upper surface of the block 161 and the holes 122 in the
block 121 (Fig. 18) are posiS:ioned so that the three holes in
,3 the front row coincide with ~he wide middle portions of the
three armature members 131 alld the four holes in the rear row
coincide with the wide middle portions of the four armature
members 132. Another block 121 is placed over the armature
members on the~lower surface of the block 161 and the holes 122
in the block are positioned so that the three holes in the
f:ront row coincide with the t~ide middle portions of the three
a:rmature members 131 and the four holes in the rear row
coincide with the wide middle portions of the four armature
members 132.
crg-83-007 ~ -19-
'
S~
A stator part 101 is located in each of the holes 122 and
the pole pieces 104, 105, 106 and 107 of these stator parts
coincide with the ridges of the sets of ridges 112 and 113 so
as to form pole pairs of the type described above with
reference to ~igs. 1, 2, 3 and ~. The lower ends of the
springs 124 engage in the holes 141 and 152 in the narrow
portions of the armature members 131, 132 remote from their
hammer heads 143, 154. All the hammer heads 143 and 154 extend
along a line X - X.
When the armature members 131, 132 are in the rest --
position, each of the armature elements 135, 136, 137 and 138
and 146, 1~7, 148 and 149 is spaced from a respective one of
the pole pairs formed by the sets of ridges 112 and 113 a~d the
pole pieces 104, 105, 106 and 107. If the coil 103 of any one
of the stator parts 102 is energized, the armature elements of
the associated armature member will be attracted into the gaps
between the adjacent pole pairs and the armature member will
move against the action of the associated spring 124. As a
result, the associated hammer head will move into a print
position.
- It will be appreciated that, since the wide middle portion
of each of the armature members 131, 132 engages in the narrow
portions of the adjacent armature members, the length of the
assembly of actuators along the line X - X is less than the sum
of the overall widths all the individual actuators. As a
result the assembly forming the hammer bank lS compact.
CT9-83-007X
